By Byron Kaye
SYDNEY, Nov 9 (Reuters) - An Australian law firm filed a class action against mining contractor Macmahon Holdings Ltd MAH.AX accusing it of misleading investors into buying its shares by withholding information about cost blowouts on a railway building project.
ACA Lawyers Pty Ltd filed the suit on Nov. 4, according to the Federal Court of Australia website, three years after the law firm says Macmahon misled investors by forecasting a rise in annual net profit, only to blame unforeseen costs for a profit downgrade a month later. The company's shares halved between the two announcements.
"Macmahon let down investors by not making timely disclosure of the financial impact of the delays and shareholders are understandably angry," ACA Lawyers principal Steven Lewis said in a statement on Monday.
Companies exposed to the Australian mining industry have found themselves at the centre of a class action boom as a commodities downturn hits profits and shares, encouraging investors to seek compensation.
ACA Lawyers is already running lawsuits against Macmahon rival WorleyParsons Ltd WOR.AX and miner Oz Minerals OZL.AX , and says it is considering an action against miner Iluka Resources Ltd ILU.AX , all over alleged breaches of disclosure rules.
The Macmahon class action is open to every person who bought its shares from May 2 to Sept. 18, 2012, the time between when the firm said it started building the railway for Rio Tinto (L:RIO) RIO.AX in the resources-rich Pilbara region of Western Australia state and when it said profit would fall up to 71 percent because of problems on that project.
The action seeks damages of about A$46 million ($32 million), Lewis said.
A Macmahon spokesman declined to comment. The company's shares were down 0.5 percent at 9 cents on Monday, before it requested a trading halt. The day after the September 2012 profit downgrade, the shares fell to 27 cents from 45 cents.
($1 = 1.4221 Australian dollars)